The percutaneous absorption of pH 9.3, 0.60 N ammonium thioglycolate was ascertained in rabbits. Applications to a clipped skin site were made daily for 20 days, and the mortality rate was followed over 3 weeks. Surfactants, mainly anionic in nature, were incorporated into the mixtures at 0.5% activity, and the LD50 or the daily dosage causing 50% mortality was determined. The lowest toxicity was displayed by mixtures with sodium oleate, sodium stearate, and alkyl aryl sulfonate (VII) (LD50: 4.1‐4.4 ml/kg); intermediate activity was found with the sodium salt of alkyl aryl polyether sulfonate (III), a protein condensation product with oleyl chloride (IV), and sodium N‐methyl‐N‐ “coconut oil acid” taurate (VI) (LD50: 3.4‐3.7 ml/kg); and the highest activity was found with technical lauryl sulfate (V), the nonionic aromatic polyglycol ether condensate (I), and the cationic alkyldimethylbenzylammonium chloride (II) (LD50: 2.3‐2.8 ml/kg). The surfactant‐free solution was relatively innocuous at 6.5 ml/kg/day. The LD50 fell with increased levels of wetting agents. The pH 9.3 sodium thioglycolate lotion with 4.0% III lowered the LD50 compared to the corresponding ammonium thioglycolate mixture. The percutaneous toxicity decreased when treatment was interrupted for several daily periods. Some insight into the penetration of 0.60 N thioglycolate through the skin was afforded by administration of the 35S‐compound at 1.0 ml/kg. The application of a pH 8.6 ammonium thioglycolate mixture with 4.0% III at 1.0 ml/kg over 20 days increased urinary 35S‐excretion; the activity fell during the last half of the tests. Although the tracer experiments showed some correlation with the general qualitative findings for several of the “cold” lotions, discrepancies were noted in relation to the LD50 values. Copyright © 1979 Wiley‐Liss, Inc., A Wiley Company
